1. Field of the Invention
This invention relates generally to pipe couplings and more particularly to such a coupling for joining a first pipe to one end of a second transverse pipe; The invention relates also to a method of fabricating the coupling.
2. Discussion of the Prior Art
As will appear from the ensuing description, the pipe coupling of the invention may be utilized for a variety of coupling applications. In its broader aspects, therefore, the invention provides an essentially general purpose pipe coupling. The preferred form of the invention is designed for securing the top pipe rails of a chain link fence to the upper ends of the fence pipe posts.
The construction of a chain link fence involves initial setting of a number of vertical fence posts, in the form of metal pipes, in the ground in spaced relation along the route of the fence with each post embedded in a concrete footing or the like. The upper ends of the adjacent posts are then joined by top rails, comprising metal pipes, which span the regions between and are secured to the upper ends of the posts. These top rails are secured to the posts by pipe couplings which are referred to in the fence industry as rail caps, eyetops, and various other names. The term rail cap is used in this disclosure. Finally, the chain link fencing is applied to complete the fence.
A wide variety of rail caps have been devised. Simply stated, such a cap comprises a sleeve-like part open at one end to form a socket for receiving the upper end of a fence post, and a transverse opening at the upper end of the part, whose axis is normally generally horizontal when the cap is installed, for receiving a top rail. The existing rail caps have various configurations and are fabricated in a number of different ways. For example, some caps are injection molded, forged or otherwise formed in one piece from aluminum or other suitable material. Other caps are fabricated in separate parts which are welded or otherwise joined. Examples of existing rail caps are found in U.S. Pat. Nos. 643,591; 1,765,651; 2,846,241; and 3,776,523.
While the existing rail caps are satisfactory to some degree, they have certain deficiencies which this invention overcomes. The foremost of these are relatively high cost of manufacture, and structural weakness which often results in cracking or damage to the caps, particularly during installation due to excessive torques and other loads inadvertently applied to the caps through the long lever arm of a top rail during its insertion through the cap. Some existing rail caps also provide very little supporting surface contact area with the top rail. Accordingly, the force per unit area is extremely high and, as a result, even the slightest abnormal twist or other load applied to the cap through a top rail may damage the cap.
As noted earlier, while the preferred embodiment of the invention is a chain link fence rail cap, the invention in its broader aspects provides a pipe coupling of general usage.